Apparatus for Improving Signal-to-Noise Performance of Projected Capacitance Touch Screens and Panels

ABSTRACT

Improved signal-to-noise performance of projected capacitance touch screens and panels is provided by an integrated circuit regulated high voltage source and high voltage/current drivers coupled to a plurality of projected capacitive touch elements that are controlled by a microcontroller. The single integrated circuit high voltage generator/driver may comprise a voltage boost circuit, a voltage reference, power-on-reset (POR), soft start, a plurality of voltage level shifters and a serial interface for coupling to the microcontroller that may control all functions related to using the projected capacitance touch screens and panels.

TECHNICAL FIELD

The present disclosure relates to projected capacitance touch screensand panels, and, more particularly, to improving signal-to-noiseperformance of the projected capacitance touch screens and panels.

BACKGROUND

Capacitive touch screens and panels are used as a user interface toelectronic equipment, e.g., computers, mobile phones, personal portablemedia players, calculators, telephones, cash registers, gasoline pumps,etc. In some applications, opaque touch screens and panels provide softkey functionality. In other applications, transparent touch screensoverlay a display to allow the user to interact, via touch or proximity,with objects on the display. Such objects may be in the form of softkeys, menus, and other objects on the display. The capacitive touchscreen or panel is activated (controls a signal indicating activation)by a change in capacitance of a capacitive electrode in the touch screenor panel when an object, e.g., a user's finger tip, causes thecapacitance of the capacitive electrode to change.

Today's capacitive touch screens and panels come in different varieties,including single-touch and multi-touch. A single-touch screen or paneldetects and reports the position of one object in contact or proximitywith the touch screen or panel. A multi-touch screen or panel detectsthe position of one or more objects in simultaneous contact or proximitywith the touch screen or panel, and reports or acts upon distinctposition information related to each object.

Touch screens and panels used in both single-touch and multi-touchsystems may comprise one or more layers, each layer having a pluralityof electrodes electrically insulated from each other. In a multi-layertouch sensor, the layers may be fixed in close proximity to andelectrically insulated from each other. In any of the one or more layertouch screen and panel constructions, the electrodes (capacitances) mayform any type of coordinate system (e.g., polar, etc.). Some touchsensors may utilize an X-Y or grid-like arrangement. Referring to FIG.1, depicted is a schematic plan view of touch sensor electrodes arrangedin an X-Y grid orientation, according to the teachings of thisdisclosure. For example, in a two-layer touch screen or panel 102,electrodes 104 and 105 are on different layers (substrate 106) and maybe arranged orthogonal to each other such that the intersectionsthereof, referred to hereinafter as nodes 120, between the electrodes104 and 105 on the different layers define a grid (or other coordinatesystem). In an alternative, single-layer touch screen, the proximityrelationship between one set of electrodes and another set of electrodesmay similarly define a grid (or other coordinate system).

Measuring the self capacitance of individual electrodes within the touchscreen or panel is one method employed by single-touch systems. Forexample, using an X-Y grid a touch sensor controller iterates througheach of the X-axis and Y-axis electrodes 105 and 104, respectively,selecting one electrode at a time and measuring its capacitance. Theposition of touch is determined by the proximity of (1) the X-axiselectrode 105 experiencing the most significant capacitance change, and(2) the Y-axis electrode 104 experiencing the most significantcapacitance change.

Performing self capacitance measurements on all X-axis and Y-axiselectrodes provides a reasonably fast system response time. However, itdoes not support tracking multiple simultaneous (X,Y) coordinates, asrequired in a multi-touch screen system. For example, in a 16×16electrode grid, the simultaneous touch by one object at position (1,5)and a second object at position (4,10) leads to four possible touchlocations: (1,5), (1,10), (4,5), and (4,10). A self-capacitance systemis able to determine that X-axis electrodes 1 and 4 have been touchedand that Y-axis electrodes 5 and 10 have been touched, but it is notcapable of disambiguating to determine which two of the four possiblelocations represent the actual touch positions.

In a multi-touch screen, a mutual capacitance measurement may be used todetect simultaneous touches by one or more objects. In the X-Y gridtouch screen, for example, mutual capacitance may refer to thecapacitive coupling between an X-axis electrode and Y-axis electrode.One set of electrodes on the touch screen may serve as receivers and theelectrodes in the other set may serve as transmitters. The driven signalon the transmitter electrode may alter the capacitive measurement takenon the receiver electrode because the two electrodes are coupled throughmutual capacitance therebetween. In this manner, the mutual capacitancemeasurement may not encounter the ambiguity problems associated withself capacitance, as mutual capacitance can effectively address everyX-Y proximity relationship (node) on the touch sensor.

More specifically, a multi-touch controller using mutual capacitancemeasurement may select one electrode in a first set of electrodes to bethe receiver. The controller may then measure (one by one) the mutualcapacitance for each transmitter electrode in a second set ofelectrodes. The controller may repeat this process until each of thefirst set of electrodes has been selected as the receiver. The positionof one or more touches may be determined by those mutual capacitancenodes, e.g., nodes 120, experiencing the most significant capacitancechange. Projected capacitive touch technology comprising self and mutualcapacitive touch detection is more fully described in Technical BulletinTB3064, entitled “mTouch™ Projected Capacitive Touch Screen SensingTheory of Operation” by Todd O'Connor, available at www.microchip.com;and commonly owned United States Patent Application Publication No. US2012/0113047, entitled “Capacitive Touch System Using Both Self andMutual Capacitance” by Jerry Hanauer; wherein both are herebyincorporated by reference herein for all purposes.

Self and mutual capacitance values may be determined by charging ordischarging voltages on the self and mutual capacitances of theelectrodes. For example, in the capacitive voltage divider (CVD) methoda capacitance value may be determined by first measuring the voltagestored on the electrode capacitor then coupling a discharged know valuecapacitor in parallel with the electrode capacitor and subsequentlymeasuring the resulting equilibrium voltage, or charging the know valuecapacitor and coupling it to a discharged electrode capacitor. The CVDmethod is more fully described in Application Note AN1208, available atwww.microchip.com; and a more detailed explanation of the CVD method ispresented in commonly owned United States Patent Application PublicationNo. US 2010/0181180, entitled “Capacitive Touch Sensing using anInternal Capacitor of an Analog-To-Digital Converter (ADC) and a VoltageReference,” by Dieter Peter; wherein both are hereby incorporated byreference herein for all purposes.

Using a Charge Time Measurement Unit (CTMU), a very accurate capacitancemeasurement of the electrode capacitance may be obtained by charging ordischarging the electrode capacitor with a constant current source thenmeasuring the resulting voltage on electrode capacitor after anaccurately measured time period. The CTMU method is more fully describedin Microchip application notes AN1250 and AN1375, available atwww.microchip.com, and commonly owned U.S. Pat. No. US 7,460,441 B2,entitled “Measuring a long time period;” and U.S. Pat. No. 7,764,213 B2,entitled “Current-time digital-to-analog converter,” both by James E.Bartling; wherein all of which are hereby incorporated by referenceherein for all purposes.

The charge, Q, on capacitance, C, is directly proportional to thevoltage, V, on the capacitance, C, according to the formula: Q=C*V.Therefore, the greater the voltage available to charge or discharge thecapacitor, the better the resolution in determining the capacitancevalues of the electrodes' self and mutual capacitances. In addition, theability to charge and discharge a capacitance with a higher (greater)voltage also improves the signal-to-noise ratio of the capacitancedetection circuit since noise is generally a constant impulse oralternating current (AC) voltage that the electrodes may be shieldedfrom to reduce noise pickup thereon. However, voltages from powersources, e.g., batteries, are being reduced to conserve power by theintegrated circuit devices. Therefore the availability of highervoltages is diminishing.

SUMMARY

Therefore, a need exists for an integrated solution that provides avoltage source having a well regulated higher output voltage that may beused for charging elements of a touch screen or panel in determiningcapacitance values thereof

According to an embodiment, an apparatus for generating a high voltageand selectively coupling the high voltage to a plurality of nodes maycomprise: a voltage boost circuit having a high voltage output; avoltage reference coupled to the voltage boost circuit; a plurality ofvoltage level shifters/drivers, each one having a high voltage inputcoupled to the high voltage output of the voltage boost circuit and anindependently controllable high voltage output; logic circuits coupledto the plurality of voltage level shifters/drivers, wherein the logiccircuits control the high voltage outputs thereof; and aserial-to-parallel interface coupled to the logic circuits and thevoltage boost circuit.

According to a further embodiment, a power-on-reset (POR) circuit may becoupled to the voltage boost circuit and the serial-to-parallelinterface. According to a further embodiment, a soft start circuit maybe coupled to the voltage boost circuit. According to a furtherembodiment, the logic circuits may be a plurality of AND gates.According to a further embodiment, an output enable control may becoupled to an input of each one of the plurality of AND gates. Accordingto a further embodiment, a high voltage output capacitor may be coupledbetween the output of the voltage boost circuit and a power sourcecommon. According to a further embodiment, a boost inductor may becoupled between a power input to the voltage boost circuit and a powersource. According to a further embodiment, the outputs of the pluralityof voltage level shifters/drivers may be tri-state and having selectableoutput states at a power source common, the high voltage output or ahigh off resistance.

According to a further embodiment, the serial-to-parallel interface mayfurther comprise configuration and data storage registers, wherein theconfiguration register stores parameters of the voltage boost circuit,and the data storage register stores output states of the plurality ofvoltage level shifters/drivers. According to a further embodiment,during a soft start the outputs of the plurality of voltage levelshifters/drivers may be disabled. According to a further embodiment, thevoltage boost circuit, the voltage reference, the plurality of voltagelevel shifters/drivers, the logic circuits and the serial-to-parallelinterface may be provided in a single integrated circuit device.According to a further embodiment, the logic circuits and input circuitsof the plurality of voltage level shifter/drivers may comprise lowvoltage and low power devices. According to a further embodiment, outputcircuits of the plurality of voltage level shifter/drivers may comprisehigh voltage devices having low impedance drive capabilities.

According to another embodiment, a system for determining locations oftouches detecting touches on a projected capacitance touch sensingsurface may comprise: a first plurality of electrodes arranged in aparallel orientation having a first axis, wherein each of the firstplurality of electrodes may comprise a self capacitance; a secondplurality of electrodes arranged in a parallel orientation having asecond axis substantially perpendicular to the first axis, the firstplurality of electrodes may be located over the second plurality ofelectrodes and form a plurality of nodes that may comprise overlappingintersections of the first and second plurality of electrodes, whereineach of the plurality of nodes may comprise a mutual capacitance; a highvoltage generator/driver may comprise a voltage boost circuit having ahigh voltage output, a voltage reference coupled to the voltage boostcircuit, a plurality of voltage level shifters/drivers, each one havinga high voltage input coupled to the high voltage output of the voltageboost circuit and an independently controllable high voltage outputcoupled to a respective one of the first and second plurality ofelectrodes, logic circuits coupled to the plurality of voltage levelshifters/drivers, wherein the logic circuits control the high voltageoutputs thereof, and a serial-to-parallel interface coupled to the logiccircuits and the voltage boost circuit; a mixed signal device maycomprise a capacitive touch analog front end having a plurality ofanalog inputs coupled to respective ones of the first and secondplurality of electrodes, an analog-to-digital converter (ADC) coupled tothe capacitive touch front end, a digital processor and memory, whereinat least one output from the ADC may be coupled to the digitalprocessor; and a serial interface coupled to the digital processor andthe serial-to-parallel interface of the high voltage generator/driver;wherein values of the self capacitances may be measured using the highvoltage for each of the first plurality of electrodes by the analogfront end, the values of the measured self capacitances may be stored inthe memory, values of the mutual capacitances of the nodes of at leastone of the first electrodes having at least one of the largest values ofself capacitance may be measured using the high voltage by the analogfront end, the values of the measured mutual capacitances may be storedin the memory and the digital processor uses the stored self and mutualcapacitance values for determining locations of the touches and therespective forces applied to the touch sensing surface.

According to a further embodiment, the mixed signal device may be amixed signal microcontroller integrated circuit. According to a furtherembodiment, the high voltage generator/driver may comprise an integratedcircuit. According to a further embodiment, the high voltage may begreater than a supply voltage powering the high voltage generator/driverand the mixed signal device.

According to yet another embodiment, a method for improvingsignal-to-noise performance of a projected capacitance touch sensingsurface may comprise the steps of: providing a first plurality ofelectrodes arranged in a parallel orientation having a first axis,wherein each of the first plurality of electrodes may comprise a selfcapacitance; providing a second plurality of electrodes arranged in aparallel orientation having a second axis substantially perpendicular tothe first axis, the first plurality of electrodes may be located overthe second plurality of electrodes and form a plurality of nodes thatmay comprise overlapping intersections of the first and second pluralityof electrodes, wherein each of the plurality of nodes may comprise amutual capacitance; charging the first plurality of electrodes to avoltage greater than a power source voltage; discharging the secondplurality of electrodes to a power source common; scanning the firstplurality of electrodes for determining values of the self capacitancesthereof; comparing the values of the scanned self capacitances todetermine which one of the first plurality of electrodes has the largestvalue of self capacitance; scanning the nodes of the one of the firstplurality of electrodes having the largest value of self capacitance fordetermining values of the mutual capacitances of the respectiveplurality of nodes; comparing the values of the scanned mutualcapacitances of the respective plurality of nodes on the first electrodehaving the largest value of self capacitance, wherein the node havingthe largest value of mutual capacitance may be a location of a touch onthe touch sensing surface.

According to a further embodiment of the method, the self and mutualcapacitance values may be measured with an analog front end and ananalog-to-digital converter (ADC). According to a further embodiment ofthe method, the self and mutual capacitance values may be stored in amemory of a digital processor. According to a further embodiment of themethod, the self and mutual capacitance values may be determined by acapacitive voltage divider method. According to a further embodiment ofthe method, the self and mutual capacitance values may be determinedwith a charge time measurement unit.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present disclosure may be acquiredby referring to the following description taken in conjunction with theaccompanying drawings wherein:

FIG. 1 illustrates a schematic plan view of touch sensor electrodesarranged in an X-Y grid orientation, according to the teachings of thisdisclosure; and

FIG. 2 illustrates a schematic block diagram of an electronic systemhaving a projected capacitance touch screen or panel, a high voltagesource/driver and a mixed signal device, according to a specific exampleembodiment of this disclosure.

While the present disclosure is susceptible to various modifications andalternative forms, specific example embodiments thereof have been shownin the drawings and are herein described in detail. It should beunderstood, however, that the description herein of specific exampleembodiments is not intended to limit the disclosure to the particularforms disclosed herein, but on the contrary, this disclosure is to coverall modifications and equivalents as defined by the appended claims.

DETAILED DESCRIPTION

According to various embodiments, an integrated solution for providing aregulated high voltage source and high voltage/current drivers forcoupling to a plurality of projected capacitive touch elementscontrolled by a microcontroller is disclosed herein. Wherein a singleintegrated circuit high voltage generator/driver may comprise a voltageboost circuit, a voltage reference, power-on-reset (POR), soft start, aplurality of low input current voltage level shifters and a serialinterface for coupling to a microcontroller that may control allfunctions related to using projected capacitance touch screens andpanels. It is contemplated and within the scope of this disclosure thatthe aforementioned high voltage generator/driver may also be used todrive high voltage low power displays such as, for example but is notlimited to, a vacuum fluorescent display (VFD), a organic light emittingdiode (OLED) display, etc.

Referring now to the drawing, the details of a specific exampleembodiment is schematically illustrated. Like elements in the drawingswill be represented by like numbers, and similar elements will berepresented by like numbers with a different lower case letter suffix.

Referring to FIG. 2, depicted is a schematic block diagram of anelectronic system having a projected capacitance touch screen or panel,a high voltage source/driver and a mixed signal device, according to aspecific example embodiment of this disclosure. A mixed signal device212 may comprise a capacitive touch analog front end 210, ananalog-to-digital converter 208, a digital processor and memory 206, anda serial interface 232. A high voltage generator/driver 214 may comprisea voltage boost circuit 216, a voltage reference 218, power-on-reset(POR) 220, a soft start circuit 222, a plurality of voltage levelshifters 224, control logic 234 to control drive from the level shifters224 to the electrodes 104 and 105, and a serial-to-parallel interface226 for coupling control of the level shifters to a serial interface 232in the mixed signal device 212. The POR 220 may be used to initializeall memory (storage) elements in the high voltage generator/driver 214during a power on start-up.

The analog front end 210 of the mixed signal device 212 and the highvoltage generator/driver 214 may be coupled to a touch screen or panel102 comprised of a plurality of conductive columns 104 and rows 105arranged in a matrix. It is contemplated and within the scope of thisdisclosure that the conductive rows 105 and/or conductive columns 104may be printed circuit board conductors, wires, Indium Tin Oxide (ITO)coatings on a clear substrate, e.g., display/touch screen, etc., or anycombinations thereof. The mixed signal device 212 may comprise amicrocontroller, digital signal processor, application specificintegrated circuit (ASIC), programmable logic array (PLA), etc.,provided in one or more integrated circuits, packaged or unpackaged (notshown). The high voltage generator/driver 214 may be provided in asingle integrated circuit, packaged or unpackaged (not shown).

The voltage boost circuit 216 generates a high voltage (HV) from a powersource VDD using a modulated input signal (Osc) in combination withexternal capacitance 228 and inductance 230. A voltage reference 218 mayprovide a constant reference voltage to the voltage boost circuit 216 sothat HV generated therefrom remains at substantially the same voltagethroughout operation of the touch screen or panel 102. The voltage boostcircuit 216 may further incorporate current limiting. The voltage boostcircuit 216 may be, for example but is not limited to, a switch modeboost power circuit, well know to one having ordinary skill in thedesign art of integrated circuit power supplies. The HV output from thevoltage boost circuit 216 is coupled to the level shifters 224, whereinAND gates 234 control the HV drive outputs of the level shifters 224that may be coupled to the electrodes 104 and 105. The output enable,OE, may be used to enable/disable the outputs of the level shifters 224as a group, and outputs of individual level shifters 224 may becontrolled by the stored contents of a shift register in theserial-to-parallel interface 226 through the AND gates 234. It iscontemplated and within the scope of this disclosure that other logicdesigns instead of AND gates may be used with equal effectiveness, andone having ordinary skill in digital logic design and the benefit ofthis disclosure would readily understand how to do so. The logiccircuits (e.g., AND gates 234) and the input circuits of the levelshifters 224 may comprise low voltage and high impedance circuits toconserve power, and the output circuits of the level shifters 224 maycomprise high voltage/current output circuits and components (not shown)having a low impedance to quickly charge the electrode capacitor(s) tothe high voltage.

The serial-to-parallel interface 226 may be, for example but is notlimited to, an industry standard shift register plus latch type serialinterface (SPI), etc. The serial-to-parallel interface 226 may be usedto configure the parameters of the voltage boost circuit 216 through acontrol bus therebetween and select active output channels, e.g.,through the AND gates 234 and level shifters 224. A clock and a serialdata stream from the serial interface 232 may be used to configure ashift register (not shown) in the serial-to-parallel interface 226 priorto latching the desired data using a Latch Enable (LE) input. Data maybe shifted as the most significant bit (MSB) first or last. Either aconfiguration word or a data word may be clocked in and latched in theserial-to-parallel interface 226. A data word selects the output stateof each level shifter driver 224. In a user mode a configuration wordmay select the boost voltage and current limit parameters of the voltageboost circuit 216.

A soft start circuit 222 may be coupled to the voltage boost circuit216. The soft start circuit 222 may be used to prevent high initialinrush current from pulling down the power source, VDD, and causing abrown out condition. For example, during the first 10 to 50 millisecondsafter the voltage boost circuit 216 is enabled, only the smallestsection of a switching transistor thereof may become active and thecurrent may, for example, be limited to a maximum of 200 milliamperes(nominal). The outputs of the level shifters 224 may also be tri-statedduring this time. After the soft start has timed out the current limitand switching transistor settings revert to a normal operating valueselected by the configuration word. Soft start may also be completelydisabled. The current limiting during soft start may be disabled.wherein the smallest sections of the switching transistors are selectedand the outputs thereof are tri-stated, but the current limiting circuitis not active.

While embodiments of this disclosure have been depicted, described, andare defined by reference to example embodiments of the disclosure, suchreferences do not imply a limitation on the disclosure, and no suchlimitation is to be inferred. The subject matter disclosed is capable ofconsiderable modification, alteration, and equivalents in form andfunction, as will occur to those ordinarily skilled in the pertinent artand having the benefit of this disclosure. The depicted and describedembodiments of this disclosure are examples only, and are not exhaustiveof the scope of the disclosure.

1-13. (canceled)
 14. A system for determining locations of touchesdetecting touches on a projected capacitance touch sensing surface, saidsystem comprising: a first plurality of electrodes arranged in aparallel orientation having a first axis, wherein each of the firstplurality of electrodes comprises a self capacitance; a second pluralityof electrodes arranged in a parallel orientation having a second axissubstantially perpendicular to the first axis, the first plurality ofelectrodes are located over the second plurality of electrodes and forma plurality of nodes comprising overlapping intersections of the firstand second plurality of electrodes, wherein each of the plurality ofnodes comprises a mutual capacitance; a high voltage generator/drivercomprising a voltage boost circuit having a high voltage output, avoltage reference coupled to the voltage boost circuit, a plurality ofvoltage level shifters/drivers, each one having a high voltage inputcoupled to the high voltage output of the voltage boost circuit and anindependently controllable high voltage output coupled to a respectiveone of the first and second plurality of electrodes, logic circuitscoupled to the plurality of voltage level shifters/drivers, wherein thelogic circuits control the high voltage outputs thereof, and aserial-to-parallel interface coupled to the logic circuits and thevoltage boost circuit; a mixed signal device comprising a capacitivetouch analog front end having a plurality of analog inputs coupled torespective ones of the first and second plurality of electrodes, ananalog-to-digital converter (ADC) coupled to the capacitive touch frontend, a digital processor and memory, wherein at least one output fromthe ADC is coupled to the digital processor; and a serial interfacecoupled to the digital processor and the serial-to-parallel interface ofthe high voltage generator/driver; wherein values of the selfcapacitances are measured using the high voltage for each of the firstplurality of electrodes by the analog front end, the values of themeasured self capacitances are stored in the memory, values of themutual capacitances of the nodes of at least one of the first electrodeshaving at least one of the largest values of self capacitance aremeasured using the high voltage by the analog front end, the values ofthe measured mutual capacitances are stored in the memory and thedigital processor uses the stored self and mutual capacitance values fordetermining locations of the touches and the respective forces appliedto the touch sensing surface.
 15. The system as recited in claim 14,wherein the mixed signal device is a mixed signal microcontrollerintegrated circuit.
 16. The system as recited in claim 14, wherein thehigh voltage generator/driver comprises an integrated circuit.
 17. Thesystem as recited in claim 14, wherein the high voltage is greater thana supply voltage powering the high voltage generator/driver and themixed signal device.
 18. A method for improving signal-to-noiseperformance of a projected capacitance touch sensing surface, saidmethod comprising the steps of: providing a first plurality ofelectrodes arranged in a parallel orientation having a first axis,wherein each of the first plurality of electrodes comprises a selfcapacitance; providing a second plurality of electrodes arranged in aparallel orientation having a second axis substantially perpendicular tothe first axis, the first plurality of electrodes are located over thesecond plurality of electrodes and form a plurality of nodes comprisingoverlapping intersections of the first and second plurality ofelectrodes, wherein each of the plurality of nodes comprises a mutualcapacitance; charging the first plurality of electrodes to a voltagegreater than a power source voltage; discharging the second plurality ofelectrodes to a power source common; scanning the first plurality ofelectrodes for determining values of the self capacitances thereof;comparing the values of the scanned self capacitances to determine whichone of the first plurality of electrodes has the largest value of selfcapacitance; scanning the nodes of the one of the first plurality ofelectrodes having the largest value of self capacitance for determiningvalues of the mutual capacitances of the respective plurality of nodes;comparing the values of the scanned mutual capacitances of therespective plurality of nodes on the first electrode having the largestvalue of self capacitance, wherein the node having the largest value ofmutual capacitance is a location of a touch on the touch sensingsurface.
 19. The method as recited in claim 18, wherein the self andmutual capacitance values are measured with an analog front end and ananalog-to-digital converter (ADC).
 20. The method as recited in claim19, wherein the self and mutual capacitance values are stored in amemory of a digital processor.
 21. The method as recited in claim 19,wherein the self and mutual capacitance values are determined by acapacitive voltage divider method.
 22. The method as recited in claim19, wherein the self and mutual capacitance values are determined with acharge time measurement unit.
 23. The method according to claim 18,wherein the voltage greater than a power source voltage is generated by:coupling a voltage reference to a voltage boost circuit; generating ahigh voltage by the voltage boost circuit; coupling high voltage inputsof a plurality of voltage level shifters/drivers to a high voltageoutput of the voltage boost circuit, wherein the plurality of voltagelevel shifters/drivers each comprise an independently controllable highvoltage output; coupling logic circuits to the plurality of voltagelevel shifters/drivers, wherein the logic circuits control the highvoltage outputs thereof.
 24. The method as recited in claim 23, furthercomprising: providing a serial-to-parallel interface coupled to thelogic circuits and the voltage boost circuit, and coupling apower-on-reset (POR) circuit to the voltage boost circuit and theserial-to-parallel interface.
 25. The method as recited in claim 23,wherein the logic circuits are a plurality of AND gates, the methodfurther comprising: coupling an output enable control to an input ofeach one of the plurality of AND gates.
 26. The method as recited inclaim 23, further comprising: coupling a high voltage output capacitorbetween the output of the voltage boost circuit and a power sourcecommon.
 27. The method as recited in claim 23, further comprising:coupling a boost inductor between a power input to the voltage boostcircuit and a power source.
 28. The method as recited in claim 23,wherein the outputs of the plurality of voltage level shifters/driversare tri-state and having selectable output states at a power sourcecommon, the high voltage output or a high off resistance.
 29. The methodas recited in claim 24, wherein the serial-to-parallel interface furthercomprises configuration and data storage registers, the method furthercomprising: storing parameters of the voltage boost circuit and outputstates of the plurality of voltage level shifters/drivers in theconfiguration and data storage register.
 30. The method as recited inclaim 23, further comprising: disabling during a soft start the outputsof the plurality of voltage level shifters/drivers.
 31. The method asrecited in claim 23, wherein the logic circuits and input circuits ofthe plurality of voltage level shifter/drivers comprise low voltage andlow power devices.
 32. The method as recited in claim 23, wherein outputcircuits of the plurality of voltage level shifter/drivers comprise highvoltage devices having low impedance drive capabilities.